Hydroponic growing

Hydroponic growing

Hydroponic Gardening for Beginners

Hydroponics is a method of growing plants without soil, using a highly oxygenated solution of nutrients circulating continuously over the plant roots. Plants may be grown with or without inert medium, such as soilless potting mixes, expanded clay aggregates, perlite, and vermiculite, gravel, sand or Rockwool.

The Benefits of Hydroponics

Hydroponics has several advantages over soil gardening. Because the plant can be supplied ideal nutrient concentrations and ratios in the hydroponic solution, the growth rate of a plant can be up to 50% faster than a plant grown under the same conditions in soil. This results in higher yields, and in some cases better tasting and more nutrient rich produce. It doesn’t require a yard to start growing. You can grow indoor year round and harvest several times a year. Hydroponic growing uses much less water than growing in soil, due to the reuse of the nutrient solutions and reduced evaporation.

Plant roots require oxygen for cellular respiration and aerated hydroponic solution provides optimum oxygen and plant nutrients, resulting in optimum plant growth. General opinion suggests that hydroponic plants also have fewer problems with insects, mites and diseases. In general, plants grown hydroponically are healthier and more nutritious.

Growing Mediums

Growing medium is an inert substance that helps support the root system of plants and channels the nutrient solution. Though you can grow without inert medium, if you decide to grow with it there are different options to choose from depending on the type of hydroponic system you use.

Expanded clay aggregate (Hydrocorn) and grow stones made from glass waste are fast draining, porous, reusable mediums that are popular for ebb and flow, and top irrigation systems.

Rockwool is a popular inert, though non-reusable growing medium. It is a mineral fiber that is pressed into growing cubes and blocks.

It is a mineral fiber that is pressed into growing cubes and blocks. Rockwool can be used in almost any hydroponic system as it retains 10-14 times more water than soil does and holds 20% air. Rockwool should be soaked in pH balanced water before use.

Other commonly used growing mediums are perlite, vermiculite, peat based soilless potting mixes, sand and gravel. These mediums don’t usually affect the pH, however they can hold too much moisture and should be used carefully. These growing mediums are very affordable, although not the most effective ones.


A hydroponic nutrient solution is one of the basics of a hydroponic system and contains the elements that the plant normally gets from the soil. Any good hydroponic nutrient should be easily soluble in water and contain Nitrogen (N), Phosphorous (P), Potassium (K), Calcium (Ca), Sulphur (S), Magnesium (Mg), Iron (Fe), Copper (Cu), Zinc (Zn), Manganese (Mn), Molydenum (Mo), Boron (B), and Chlorine (Cl). Nutrients are usually highly concentrated and come in liquid or powered mixes with different containers to allow a grower to manipulate ratio depending on a crop and its life stage.


pH is a unit of measure that describes the degree of acidity of a solution. pH requirements differ depending on a plant, yet most plants can grow hydroponically within a pH range of 5.8 to 6.8. The pH balance of nutrient solution is essential, as it affects how well plants can absorb the nutrients in water.

Testing pH in a hydroponic system is a lot easier than in soil. It can be done by using a pH testing kit or a pH testing meter. pH balance should be checked once a week and adjusted by adding small amounts of soluble Potash to raise pH, or phosphoric acid to lower pH.


PPM stand for “parts per million” and is used to measure the strength of the nutrient solution that is contain with your hydroponic system. When growing cannabis your ideal PPM range is from 300-1600 depending on what stage in the lifecycle your plant is in. When measuring PPM you will want to have a TDS (Total Dissolved Solids) meter which will identify the PPM of your nutrient solution. The most important reason to monitor your PPM levels in nutrient solutions is to prevent nutrient burn. PPM levels over 1600 is likely going to burn your cannabis plant. Growers who run higher level PPM’s are most likely supplementing with C02.

Hydroponic Systems

Hydroponic plants need three basic things to thrive: water, oxygen and nutrients. There are various types of hydroponic systems that differ in how they deliver these essential components to the plants’ roots. All hydroponic systems fall into two categories: active and passive. An active hydroponic system usually uses a pump to actively move the nutrient solution. In a passive hydroponic system, the nutrient solution is absorbed by the medium and passed along to the roots. This type of system is often too wet and does not supply enough oxygen to the root system. Active hydroponic systems are the most common.

Hydroponic systems can also be divided into recovery and non-recovery systems. Recovery (or recirculating) systems reuse the nutrient solution. In non-recovery systems, the nutrient solution is applied to the growing medium and not recovered. Non-recovery systems often use soilless potting mixes, and are sometimes referred to as ‘semi-hydroponics’.

Plant life cycle


Cannabis is unusual in the plant kingdom in that is it dioecious, which means that it produces male and female flowers on separate plants. Female plants will produce flowers that are often referred to as buds. The male plants produce flower clusters that contain pollen that is used for pollinating female plants. When this occurs the female plant will produce seeds within the buds, but by pollinating a female plant you lower the potency of THC content. This I why most growers choose to either grow from a “clone” (which is a cutting taken from a female plant to replicate genetics) or they will grow what is called “Sinsemilla”. Sinsemilla is a feminized seeds that will only produce female plants and all genetics within the genetics will be uniform. All seeds should always be stored in a cool dark place and using a desiccate like rice will reduce moisture and help retain 80%+ germination rate for up to 5 years.


This is the first stage that the cannabis plant enter after it has been germinated. Most growers will use a substrate such as Rockwool to plant their seeds for germination. Germination can take up to 10 days before the plant breaks the surface. When germinating seeds it is important to remember that the environment should be warm (70-78 °F*) and the humidity should be kept around 80%. Once your seed breaks the surface you have entered the seedling stage. Depending on the type of substrate that is used nutrients are usually not necessary in this stage. At this stage the plant is very vulnerable to and it is important to monitor your plant closely over the next several days. The first leaves you will see are actually lobes in the stage and the plant does not move into vegetation stage until it receives it first set of true leaves.

Vegetative Stage

Once your plant has grown its first set of “true leaves” it begins to enter what is called the vegetative stage.

This is the stage where your plant will focus on both vertical growth and also begin to bush out. This stage is very important as the healthier the plant is and the less stress it receives the greater yield for the grower. During this stage cannabis is given anywhere from 18-24 hours of light, temperatures of 75-80 °F*, and a humidity level of around 60*-70 °F*. This will allow the cannabis to thrive in its environment and establish both a strong root system and will begin to produce foliage through photosynthesis. During this stage most growers have to start feeding nutrients and it is recommended that plants be given higher doses of nitrogen and lower doses of phosphorous and potash. Most plants are kept in this stage from 4-6 weeks, but it is important to keep track of your plants height as some plants can triple in size when entering the flowering stage. Growers with height limitation will use techniques such as SOG (Sea of Grow) or Topping to create a “bushing” effect. This allows the grower to not only slow down vertical growth, but will also help increase the yield by creating more than one cola (terminal bud). The main cola (sometimes called the apical bud) forms at the very top of the plant, while smaller colas occur along the budding sites below. 

The last week of the vegetative stage is where you will sex your plant and remove any unwanted males if you are growing sinsemilla plants in your flowering stage.

Flowering Stage

When your plant is ready to flower you want to begin by changing your lighting cycle to 12/12. This will trigger the plant to begin producing flower clusters or “buds”. During this stage temperatures should still be kept between 75*-80* °F, but humidity should be reduce to as low as 10% as this will reduce the risk of bud rot or mold. During this stage growers will also reduce their levels of nitrogen and increase their levels of phosphorous and potash. If you are wanting to crossbreed cannabis this is the stage where you will use your male cannabis plant to pollenate your female plants. During the first 1-3 weeks your plant will begin to stretch and focus on vertical growth. During week 4 you will begin to see your plant begin to form bud sites and also flower clusters. This will continue for up to 16 weeks if you’re growing a sativa, or as short as 8 weeks if you’re growing an indica. It is important at this stage to monitor your trichrome production, as this will signal when your plant is ready to harvest. When the trichromes are clear the plant is still maturing. Most growers wait until 20% of plant has amber trichromes before they harvest. If you harvest earlier or too late potency will be reduced.